An object of the present invention is to provide reducing steam that prevents "oxidation" which is a cause of quality deterioration generated during heating processing of foods and the like. A hydrogen gas is added to a high-temperature heated steam of 100 ° C. or more at a volume ratio of 1% or more and 20% or less to generate reductive steam having a strong reducing power at high temperatures to an object based on the reducing power of hydrogen. I do. The antioxidant functional substance of the object is protected by spraying the food or the like. [Selection] Figure 1【課題】食品等の加熱加工に際して発生する、品質低下の原因である「酸化」を防止する還元性水蒸気の提供。【解決手段】１００℃以上の高温加熱蒸気へ水素ガスを容積比で１％以上２０％以下添加注入し、水素の還元力に基づき、高温で対象物へ強い還元力を有する還元性水蒸気を生成する。食品等に対するその噴射で対象物の抗酸化機能性物質を保護する。【選択図】図１
